If your home isn’t the right temperature, no matter how often you adjust the thermostat, it may not be time to summon an HVAC contractor. Thermostats can malfunction or break but this is typically unusual. Many issues can be fixed with DIY thermostat repair. We’ll detail some tasks you can do before thinking about hiring a professional.
Check the Circuit Breaker or Thermostat Setting
A lack of heating or cooling can be due to a tripped circuit breaker. Resetting a tripped breaker will restore function if that’s the only cause of the problem. And if the thermostat is set to the wrong mode (i.e., “Heat” instead of “Cool” or vice versa), it’s not set at the desired temperature, or it’s turned off, adjusting it accordingly can resolve the matter without doing anything else.
Turn the Temperature Up or Down
Does your thermostat seem unresponsive? Try setting it 5℉ lower if it’s summer or 5℉ higher in winter. After doing so, you should hear a click and your HVAC unit should respond. Air should start blowing from the supply registers within a few minutes.
Replace the Battery
If the AC or furnace isn’t running, check whether the thermostat is on. Change the battery if a digital unit keeps turning off or appears weak. The owner’s manual should tell you how to do and the type of battery to use.
Fix Loose or Disconnected Wires
To access the wires, gently grab and pull the cover off the unit. Some models have a button or clip to open the cover. For line-voltage thermostats, turn off the circuit breaker first. Then you can inspect for loose connections.
Reconnect any wire that’s not attached to its terminal and tighten anything that appears loose, using a screwdriver. Grip wires with needle nose pliers to move or twist them in place around screws. If any wires are damaged, replace them.
Clean the Thermostat
Older mechanical thermostats are particularly susceptible to dirt. Dust can get in the lever and in the bi-metal coil. Use a small brush or cloth to wipe down components or use a can of compressed air. Blow air to remove dust when the thermostat is at its lowest setting and when it’s set to high. Small metal contacts can be cleaned by sliding a piece of paper between each.
Level the Unit
If it’s mounted unevenly, a thermostat won’t work properly, especially if it uses a mercury switch (it’s also best if digital or programmable models are level too). Using a torpedo level, reposition the unit so it is completely level. While you’re at it, check for drafts or if a vent is obstructed. Eliminating drafts and obstructions (or relocating the thermostat) can fix the problem.
Test the Terminals
Wires are held in place by screw terminals. These are where the colored wires wrap around to form a connection. There are wires for the fan, AC, heater, and a 24-volt wire from the transformer. Find a piece of low voltage wire with a stripped end. Set the thermostat to “Auto” and touch it to the transformer and heater wire; then do the same in “Heat” mode.
There should be no response when you do this. If the heater begins to run, there’s nothing you can do to fix the thermostat. The time has come to replace it.
Perform a Transformer Test
The thermostat is connected to a transformer to lower the supplied voltage that reaches it. The transformer may be inside the furnace access panel or near the heater or air conditioner. You’ll need a multimeter to test it. Set the tool to 50 VAC and touch one probe to the top of the transformer screw heads. If no current is detected, the transformer is faulty and must be replaced.
Contact Sky Heating & Air Conditioning
In addition to professional air conditioner and furnace installation, repair, and maintenance, our licensed technicians can also provide thermostat repair. They can quickly troubleshoot the unit and correct any issue. If necessary, it can be replaced with a programmable or smart thermostat to improve efficiency. Modern thermostats offer a greater degree of control and convenience; some can even be managed remotely. For repairs or recommendations, call 503-673-9083 today.